Sex selection embraces attempts to choose or influence the sex of a child before pregnancy, during pregnancy, and after birth (infanticide). This paper examines these issues from an international human rights perspective and considers whether human rights laws are permissive or prohibitive with regard to sex selection. It discusses some of the ethical views on the matter. India and the UK are used as case studies. In both countries sex selection is - roughly speaking - prohibited, but the difference is that, while in India there is widespread practice of 'son preference', in the UK reasons for choosing to sex select are mostly because of 'family balancing'. The key question is whether choosing the sex of one's child is inherent in the right of reproductive choice, which is an important principle under international human rights law. It will be concluded that international human rights law does not recognise a right to 'sex selection'. Rather, international human rights law is generally geared towards prohibiting sex selection based on the assumption that it enhances discrimination of women. On this basis it is argued that a right to choose the sex of one's child is not an element of women's 'right of reproductive choice', which stipulates a right to choose the number and spacing of one's children, not the sex. Based on these findings this article argues that international human rights law provides strong legal and moral grounds for prohibiting sex selection, in particular in countries like India where there is extensive practice of sex selection. In countries like the UK, where the current main reason to sex select is for 'family balancing', the basis for prohibition under international human rights law is not as strong, yet several reasons can be put forward to nonetheless prohibit the practice.